An apparatus to connect and seal two duct sections is well known. Such an apparatus comprises first and second connectors, one connector attached to each duct section. A flange extends from each connector, and the flanges of the two connectors are fastened together, thereby making the connection. More particularly, each connector includes a tubular member having an inside diameter incrementally less (or greater) than an inside (or outside) diameter of a round or round oval duct. A radially directed annular flange extends from the tubular member. The flanges of the first and second connectors are typically secured together by a plurality of fasteners, such as sheet metal screws, distributed evenly about the flange. A washer or gasket may be carried between the flanges, to improve the seal.
The use of such a structure for connecting and sealing two duct sections is very widespread. Unfortunately, the performance of such an apparatus suffers from several problems. First, there is a tendency for the tubular member of the connecting and sealing connector to bend, and therefore to improperly fit the duct to which is it to be installed. Secondly, the flange directed outward in a radial direction may also bend, and therefore not properly fit flush against the flange of the other connector, or against the gasket carried between the flanges. Third, the outer edges of the flanges are often sharp, and care must be taken during handling to avoid injury to the installation technician and to avoid damage to other objects.
In some applications where duct sealer is used, excess duct sealer is squeezed from between the flanges as the fasteners are tightened, and tends to foul the perimeter of the apparatus.
For the foregoing reasons, there is a need for an apparatus for connecting and sealing adjacent duct sections that can overcome the disadvantages of the prior art. The apparatus for connecting and sealing two adjacent duct sections must resist deformation of both the tubular member and also the flange directed outward in a radial direction. The structure must provide for the maintenance of a gas-tight seal both between adjacent flanges, and also between the tubular member and the duct to which it is connected. The flanges must be adapted for use with conventional gaskets and duct sealers, but should additionally provide structures which result an additional barrier to gas transfer into or out of the connected ducts. The flanges must also be adapted for optional installation of additional hardware to increase the resistance of the flange to bending, for use in applications where bending is more likely to result. Additionally, some structure may be provided that contains excess duct sealer squeezed from between the flanges when the fasteners are tightened, to prevent fouling of the perimeter of the apparatus.